Hydrogen-free sodium hypochlorite preparation system and sodium hypochlorite preparation process

Abstract

The invention belongs to the technical field of sodium hypochlorite preparation, and provides a hydrogen-free sodium hypochlorite preparation system and a sodium hypochlorite preparation technology.The sodium hypochlorite preparation system comprises a brine electrolysis device, and a liquid inlet of the brine electrolysis device communicates with a pipeline mixer through an electrolyte conveying pipeline; a liquid inlet of the pipeline mixer is respectively communicated with a saturated salt water preparation device and a saturated salt water dilution device, a liquid outlet of the salt water electrolysis device is communicated with a sodium hypochlorite storage tank through a sodium hypochlorite conveying pipeline, and a liquid outlet of the sodium hypochlorite storage tank is communicated with a metering and adding device; the brine electrolysis device comprises an air cathode electrolytic cell and a rectification power supply, the air cathode electrolytic cell comprises a cell body, the cell body is provided with a containing cavity for containing electrolyte, and an anode and a cathode which are electrically connected with the rectification power supply are fixedly installed on the cell body. According to the method, the sodium hypochlorite solution is prepared efficiently and safely, no hydrogen is generated in the electrolysis process, the operation safety is remarkably improved, and the method is safer and more environmentally friendly.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sodium hypochlorite preparation, in particular to a sodium hypochlorite preparation system without hydrogen generation and a sodium hypochlorite preparation process. BACKGROUND

[0002] Sodium hypochlorite is an inorganic chlorine-containing compound with strong oxidizing and bleaching properties, which is a commonly used chemical in daily life and industrial production, mainly used in disinfection and sterilization, bleaching, chemical oxidation and other fields. Among them, the sodium hypochlorite solution hydrolyzed after dissolving in water can destroy the protein structure and nucleic acid of bacteria and viruses, making them lose activity, and is a highly effective chlorine-containing disinfectant.

[0003] Sodium hypochlorite is widely used as an effective and environmentally friendly disinfectant for environmental and water disinfection, but it is prone to decomposition and is not conducive to long-term storage and transportation. The sodium hypochlorite generator is a water treatment disinfection and sterilization equipment, which can generate sodium hypochlorite solution by electrolyzing salt water, and can better realize the on-site preparation of sodium hypochlorite solution. However, the current sodium hypochlorite generator generates sodium hypochlorite solution by electrolyzing salt water. Under the principle of electrochemistry, hydrogen ions will get electrons at the cathode to produce hydrogen gas. The recovery rate of the generated hydrogen gas is low, and hydrogen gas is a flammable gas. When the concentration of hydrogen gas is 4.0% to 75.6% (volume concentration), it will explode when meeting fire, which has a high operation risk and a great safety hazard. In addition, the electrolyte used by the sodium hypochlorite generator is a 3% salt water solution. However, most of the current sodium hypochlorite generators do not have a matching salt water preparation device, which cannot provide the sodium hypochlorite generator with a salt water solution that meets the use requirements, thereby directly affecting the preparation efficiency and quality of the sodium hypochlorite solution. SUMMARY

[0004] In order to overcome the defects of the prior art pointed out above, after a lot of creative labor is paid, the present application is completed.

[0005] Specifically, the technical problem to be solved by the present application is to provide a sodium hypochlorite preparation system without hydrogen generation and a sodium hypochlorite preparation process, in order to solve the technical problem that the current sodium hypochlorite preparation method generates hydrogen gas during the preparation process, has high operation risk, has a great safety hazard, and has low recovery rate of hydrogen gas.

[0006] To solve the above technical problems, the technical scheme of the present application is: A sodium hypochlorite preparation system without hydrogen production includes a brine electrolysis device. The inlet of the brine electrolysis device is connected to a pipeline mixer via an electrolyte delivery pipeline. The inlet of the pipeline mixer is connected to a saturated brine preparation device and a saturated brine dilution device. The outlet of the brine electrolysis device is connected to a sodium hypochlorite storage tank via a sodium hypochlorite delivery pipeline. The outlet of the sodium hypochlorite storage tank is connected to a metering and dosing device. The brine electrolysis device includes an air cathode electrolysis cell and a rectifier power supply. At least one air cathode electrolysis cell is provided. The air cathode electrolysis cell includes a cell body with a cavity for holding electrolyte. An anode and a cathode electrically connected to the rectifier power supply are fixedly installed in the cell body. The anode includes a titanium substrate, the titanium substrate is coated with a ruthenium-iridium noble metal oxide coating, the anode is located in the receiving cavity, and the top of the anode extends out of the tank body to form an anode terminal; The cathode includes a catalyst layer, a current collector layer, and a permeable layer. The current collector layer is located between the catalyst layer and the permeable layer. The catalyst layer is close to the anode and in contact with the receiving cavity. The permeable layer is at least partially in contact with the outside. The top of the cathode extends outside the tank body to form a cathode terminal.

[0007] As an improved technical solution, the saturated brine preparation device includes a salt dissolving tank, the top of which is provided with a water inlet and a salt inlet, and the water inlet of the salt dissolving tank is connected to a water replenishment device, and the salt inlet of the salt dissolving tank is connected to a salt feeding device. The bottom of the salt dissolving tank is equipped with a salt dissolving water distribution pipe and a salt dissolving filter. The salt dissolving water distribution pipe is located above the salt dissolving filter and is connected to the upper middle part of the salt dissolving tank through a salt dissolving pipe. A salt dissolving pump is installed on the salt dissolving pipe. The outlet of the salt dissolving filter is connected to the pipe mixer through a saturated brine delivery pipe. A saturated brine metering pump, a first manual valve, and a saturated brine flow meter are sequentially installed on the saturated brine delivery pipe along the delivery direction of the saturated brine solution.

[0008] As an improved technical solution, the water replenishment device includes a water softener, the inlet of which is connected to a tap water supply pipeline, and the tap water supply pipeline is provided with a second manual valve, a first Y-type filter and a first pressure gauge in sequence along the tap water supply direction. The outlet of the water softener is connected to the water inlet of the salt dissolving tank through a water replenishment pipeline, and an ultrasonic level gauge for liquid level detection is installed on the top of the salt dissolving tank. The salt feeding device includes a salt storage hopper, a vacuum generator is provided below the salt storage hopper, the suction port of the vacuum generator is connected to the discharge port of the salt storage hopper, the liquid inlet of the vacuum generator is connected to the middle and upper part of the salt dissolving tank through a salt flushing pipe, and a salt feeding pump and a third manual valve are provided on the salt flushing pipe. The third manual valve is located between the salt feeding pump and the salt dissolving tank, and the liquid outlet of the vacuum generator is connected to the salt inlet of the salt dissolving tank through the salt feeding pipe. The salt storage hopper has an inverted conical shell structure, and a flushing spray pipe is provided inside the salt storage hopper. The flushing spray pipe has an annular structure that is adapted to the contour of the inner wall of the salt storage hopper, and several spray holes are opened on the flushing spray pipe facing the hopper wall. The flushing spray pipe is connected to the outlet of the salt pump through a flushing branch pipe, and a flushing electric valve is provided on the flushing branch pipe.

[0009] As an improved technical solution, several salt dissolving water distribution pipes are arranged side by side, and the several salt dissolving water distribution pipes are connected to the salt dissolving pipeline through a main water distribution pipe. Several water distribution holes are opened on the side of the salt dissolving water distribution pipe facing the top of the salt dissolving tank, and the several water distribution holes are evenly arranged along the length of the salt dissolving water distribution pipe. The salt-dissolving filter includes an inner support tube with several water passage holes. A filter cotton layer covering the water passage holes is provided outside the inner support tube. An outer permeable pipe is fitted over the filter cotton layer, with the inner diameter of the outer permeable pipe being larger than the outer diameter of the filter cotton layer. A filtration gap is formed between the inner wall of the outer permeable pipe and the outer wall of the filter cotton layer. The outer permeable pipe has several water passage holes, and one end of the outer permeable pipe is sealed and fixedly connected to a port plug. The other end of the outer permeable pipe is sealed and fixedly connected to a port connector. The filter cotton layer and the outer permeable pipe are located between the port plug and the port connector. A clearance hole is provided at the end of the port connector away from the port plug for the inner support tube to pass through. The end of the inner support tube away from the port plug passes through the clearance hole through the port connector and communicates with the saturated brine delivery pipeline.

[0010] As an improved technical solution, the saturated brine dilution device includes a dilution water tank. The inlet of the dilution water tank is connected to the outlet of the water softener through a soft water delivery pipe. The outlet of the dilution water tank is connected to the pipe mixer through a dilution water delivery pipe. A dilution water pump, a fourth manual valve, and a dilution water flow meter are sequentially arranged on the dilution water delivery pipe along the soft water delivery direction.

[0011] As an improved technical solution, the tank includes a connecting body, an anode holding plate is sealed and fixedly connected to one side of the connecting body, the cathode is fixedly installed on the other side of the connecting body through a cathode holding frame and is sealed to the connecting body, the catalyst layer of the cathode is disposed close to the connecting body, the air permeable layer of the cathode is close to the cathode holding frame, and the cathode holding frame has an air permeable window for enabling the cathode to contact the outside air; The connecting body, the anode holding plate, and the cathode are arranged to form the receiving cavity. The bottom of the connecting body is provided with a liquid inlet communicating with the receiving cavity, and the liquid inlet of the connecting body is connected with the electrolyte conveying pipeline. The top of the connecting body is provided with a liquid outlet communicating with the receiving cavity, and the liquid outlet of the connecting body is connected with the sodium hypochlorite conveying pipeline. The anode is located between the anode holding plate and the connecting body, and the anode is located within the receiving cavity.

[0012] As an improved technical solution, an anode clearance groove adapted to the anode is provided on one side of the connecting body. The anode is installed on one side of the connecting body through the anode clearance groove and sealed to the connecting body using an anode sealing strip. There is a communication gap between the two sides of the connecting anode and the connecting body for the electrolyte to pass through. The anode holding plate is sealed to the connecting body and the anode using an anode sealing ring. The anode holding plate has a liquid storage tank on the side near the anode. The anode divides the receiving cavity into a first chamber and a second chamber. The anode holding plate forms the first chamber by its liquid storage tank and the anode. The second chamber is formed by the anode, the connecting body, and the cathode. The first chamber and the second chamber are connected by the communication gap. The other side of the connecting body is provided with a cathode clearance groove adapted to the cathode. The cathode is installed on the other side of the connecting body through the cathode clearance groove and is sealed to the connecting body by a first cathode sealing ring. The cathode holding frame is sealed to the cathode by a second cathode sealing ring, and the cathode holding frame has an integrally formed cathode holding strip, which divides the ventilation window into several ventilation areas.

[0013] As an improved technical solution, the cathode is a layered structure formed by pressing the catalyst layer, the current collector layer, and the gas permeable layer together; wherein, The catalyst layer comprises oxygen reduction electrocatalyst powder, conductive carbon black, and hydrophobic material. The catalyst layer is a film-like structure obtained by pressing a mixture of the oxygen reduction electrocatalyst powder, the conductive carbon black, and the hydrophobic material, or a thin-layer structure obtained by hot pressing a mixture of the oxygen reduction electrocatalyst powder, the conductive carbon black, and the hydrophobic material after spraying. The breathable layer includes conductive carbon black, binder and hydrophobic material. The breathable layer is a membrane structure obtained by pressing a mixture of the conductive carbon black, the binder, the hydrophobic material and the pore-forming agent into a membrane and then decomposing and removing the pore-forming agent. The current collector layer has a titanium mesh structure.

[0014] As an improved technical solution, the metering and dosing device includes a sodium hypochlorite pumping pipeline and a sodium hypochlorite return pipeline. The sodium hypochlorite pumping pipeline is connected to the outlet of the sodium hypochlorite storage tank. Along the pumping direction of the sodium hypochlorite solution, the sodium hypochlorite pumping pipeline is sequentially equipped with a sixth manual valve, a second Y-type filter, a dosing metering pump, a second pressure gauge, and a back pressure valve. One end of the sodium hypochlorite return pipeline is connected to the outlet of the dosing metering pump, and the other end of the sodium hypochlorite return pipeline is connected to the inlet of the dosing metering pump. The sodium hypochlorite return pipeline is equipped with a pressure relief valve. The outlet of the dosing metering pump is also connected to a pulse damper through a seventh manual valve.

[0015] This invention also discloses a process for preparing sodium hypochlorite using the aforementioned hydrogen-free sodium hypochlorite preparation system, comprising the following steps: S1. Tap water is transported to the water softener. After being treated by the water softener, the softened water is transported to the salt dissolving tank and the dilution water tank in two separate streams. S2. The salt pump operates to add the salt from the salt storage hopper into the salt dissolving tank; S3. The salt dissolving pump operates to dissolve the salt in the salt dissolving tank through the salt dissolving water distribution pipe. At the same time, the salt is filtered by the salt dissolving filter to obtain a saturated salt solution. When the salt in the salt dissolving tank is insufficient, step S2 is repeated. S4. The saturated brine solution obtained after filtration through the salt dissolving filter is transported to the pipeline mixer. At the same time, the softened water in the dilution water tank is transported to the pipeline mixer. The pipeline mixer is used to mix the saturated brine solution and the softened water to obtain a dilute brine solution. S5. The dilute salt solution is fed into an air cathode electrolytic cell, and the dilute salt solution is electrolyzed in the air cathode electrolytic cell to obtain a sodium hypochlorite solution. S6. Transfer the sodium hypochlorite solution to a sodium hypochlorite storage tank for temporary storage. S7. Measure and pump the sodium hypochlorite solution in the sodium hypochlorite storage tank as needed for addition and use.

[0016] After adopting the above technical solution, the beneficial effects of the present invention are: This hypochlorous acid preparation system for electrolyzing acidic electrolytes operates by using a water softener to prepare softened water. The softened water is simultaneously delivered to a brine tank for salt dissolution and to a dilution tank for temporary storage. An automatic salt addition device adds salt to the brine tank. A brine distribution pipe and a brine filter facilitate rapid dissolution of the salt in the brine tank and online preparation of a saturated brine solution. A saturated brine metering pump then delivers the saturated brine solution, filtered through the brine filter, to a pipeline mixer. Simultaneously, a dilution water pump delivers the softened water from the dilution tank to the pipeline mixer. Under the action of the pipeline mixer, the saturated brine... Aqueous solution and softened water are thoroughly mixed to prepare a dilute salt solution. This solution then enters an air cathode electrolytic cell. A coated titanium anode is used as the anode, where a chlorine evolution reaction occurs, producing chlorine gas. A gas diffusion electrode with a three-phase interface is used as the cathode, where an oxygen reduction reaction occurs, producing sodium hydroxide. The anode and cathode products mix within the containment chamber of the air cathode electrolytic cell to generate sodium hypochlorite. Finally, the sodium hypochlorite solution is temporarily stored in a sodium hypochlorite storage tank. This process enables the online preparation of sodium hypochlorite solution. When needed, the sodium hypochlorite solution in the storage tank is metered and pumped out using a metering and dosing device for application.

[0017] This hydrogen-free sodium hypochlorite preparation system and process enables online preparation of the electrolyte and sodium hypochlorite solution via electrolysis. The system and process are simple and convenient, resulting in efficient and safe sodium hypochlorite solution preparation. The air cathode electrolyzer optimizes the electrolysis process. Compared to traditional methods that use a sodium hypochlorite generator to electrolyze brine, this air cathode electrolyzer generates sodium hypochlorite solution by electrolyzing a dilute salt solution and utilizing oxygen from the air. No hydrogen is generated during electrolysis, avoiding the risk of explosion and significantly improving operational safety. It is also safer and more environmentally friendly. Furthermore, the entire preparation process requires only simple raw materials such as electricity, water, and salt. On-site online preparation reduces transportation and storage costs, making it more economical for long-term use. It is applicable to various scenarios, such as drinking water disinfection and wastewater treatment, and its output can be adjusted according to demand to suit different scales of application. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0019] Figure 1 This is a process flow diagram of the sodium hypochlorite preparation system of the present invention that does not generate hydrogen. Figure 2 This is a process flow diagram for preparing the saturated salt solution of the present invention; Figure 3 This is a flow chart of the preparation process of the dilute salt aqueous solution of the present invention; Figure 4 This is a flow chart of the preparation and storage process of sodium hypochlorite solution according to the present invention; Figure 5 This is a schematic diagram of the installation and connection structure of the salt dissolving water distribution pipe of the present invention; Figure 6 This is a three-dimensional structural diagram of the salt dissolving filter of the present invention; Figure 7 This is a schematic diagram of the exploded structure of the salt-dissolving filter of the present invention; Figure 8 This is another exploded structural diagram of the salt-dissolving filter of the present invention; Figure 9 This is a three-dimensional structural diagram of the inner support tube of the present invention; Figure 10 This is a three-dimensional structural diagram of the filter cotton layer of the present invention; Figure 11 This is another three-dimensional structural diagram of the filter cotton layer of the present invention; Figure 12 This is a three-dimensional structural diagram of the external permeable pipe of the present invention; Figure 13 This is a three-dimensional structural schematic diagram of the air cathode electrolytic cell of the present invention; Figure 14 This is a cross-sectional view of the air cathode electrolytic cell of the present invention; Figure 15 This is a schematic diagram of the circuit and piping connection structure of the two air cathode electrolytic cells of the present invention; Figure 16 This is a schematic diagram of the exploded structure of the air cathode electrolytic cell of the present invention; Figure 17 This is a cross-sectional view of the anode and cathode of the present invention mounted on the connecting body; Figure 18 This is a three-dimensional structural diagram of the connecting body of the present invention; Figure 19 This is another three-dimensional structural diagram of the connecting body of the present invention; Figure 20 This is a three-dimensional structural diagram of the anode clamping plate of the present invention; Figure 21 This is a three-dimensional structural diagram of the cathode holding frame of the present invention; Attached reference numerals: 1-Salt dissolving tank; 2-Salt dissolving water distribution pipe; 201-Water distribution hole; 3-Salt dissolving filter; 4-Salt dissolving pipeline; 5-Salt dissolving pump; 6-Saturated brine delivery pipeline; 7-Pipeline mixer; 8-Saturated brine metering pump; 9-First manual valve; 10-Saturated brine flow meter; 11-Water softener; 12-Tap water delivery pipeline; 13-Second manual valve; 14-First Y-type filter; 15-First pressure gauge; 16-Water supply pipeline; 17-Ultrasonic level gauge; 18-Salt storage hopper; 19-Vacuum generator; 20-Salt flushing pipe; 21-Salt feeding pump; 22-Third manual valve; 23-Salt feeding pipe; 24-Flushing spray pipe; 25-Salt flushing branch pipe; 26-Salt flushing electric valve; 27-Main water pipe; 28-Support base; 29-Plug; 30-Inner support tube; 3001-Water passage hole; 31-Filter cotton layer; 32-Outer water permeable pipe; 3201-First curved rib; 3202-Second curved rib; 33-Port sealing component; 34-Port connector; 3401-Allowing hole; 35-Dilution water tank; 36-Soft water delivery pipeline; 37-Dilution water delivery pipeline; 38-Dilution water pump; 39-Fourth manual valve; 40-Dilution water flow meter; 41-Electrolyte delivery pipeline; 42-Air cathode electrolytic cell; 43-Rectifier power supply; 44-Drainage pipe; 45-Fifth manual valve; 46-Sodium hypochlorite delivery pipeline; 47-Sodium hypochlorite storage tank; 48-Connecting body; 4801-Anode clearance groove; 4802-Sealing strip mounting groove; 4803-Cathode clearance groove; 4804-Second sealing ring mounting groove; 49-Anode holding plate; 4901-Reservoir tank; 4902-First sealing ring mounting groove; 50-Anode; 51-Cathode holding frame; 5101-Cathode holding strip; 5102-Third sealing ring mounting groove; 52-Cathode; 53-Anode sealing strip; 54-Connecting gap; 55-Anode sealing ring; 56-First cathode sealing ring; 57-Second cathode sealing ring; 58-Inter-tank conveying pipe; 59 - Sodium hypochlorite pumping pipeline; 60 - Sodium hypochlorite return pipeline; 61 - Sixth manual valve; 62 - Second Y-type filter; 63 - Metering pump; 64 - Second pressure gauge; 65 - Back pressure valve; 66 - Pressure relief valve; 67 - Seventh manual valve; 68 - Pulse damper. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0022] Meanwhile, the meaning of "and / or" or "and / or" appearing throughout the text is that it includes three options. Taking "A and / or B" as an example, it includes option A, option B, or an option that satisfies both A and B.

[0023] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0024] like Figures 1 to 4 As shown in the figure, this embodiment provides a sodium hypochlorite preparation system without hydrogen generation, including a brine electrolysis device. The inlet of the brine electrolysis device is connected to a pipe mixer 7 via an electrolyte delivery pipe 41. The inlet of the pipe mixer 7 is connected to a saturated brine preparation device and a saturated brine dilution device. The outlet of the brine electrolysis device is connected to a sodium hypochlorite storage tank 47 via a sodium hypochlorite delivery pipe 46. The outlet of the sodium hypochlorite storage tank 47 is connected to a metering and dosing device. The saturated brine preparation device enables online preparation of a saturated brine solution, and the saturated brine dilution device enables online dilution of the saturated brine solution, thereby achieving online preparation of a dilute brine solution of the desired concentration. Then, the brine electrolysis device electrolyzes the dilute brine solution, and the resulting sodium hypochlorite solution is temporarily stored in the sodium hypochlorite storage tank 47. When needed, the metering and dosing device measures and pumps the sodium hypochlorite solution in the storage tank 47 for use.

[0025] like Figure 4 , Figures 12 to 17As shown, the brine electrolysis device includes an air cathode electrolyzer 42 and a rectifier power supply 43. At least one air cathode electrolyzer 42 is provided. The air cathode electrolyzer 42 includes a tank body with a cavity for holding electrolyte. An anode 50 and a cathode 52, electrically connected to the rectifier power supply 43, are fixedly mounted on the tank body. The anode 50 includes a titanium substrate with a ruthenium-iridium oxide coating. The anode 50 is located within the cavity, and its tip extends outside the tank body to form an anode terminal. The cathode 52 includes a catalyst layer, a current collector layer, and a permeable layer. The current collector layer is located between the catalyst layer and the permeable layer. The catalyst layer is close to the anode 50 and in contact with the cavity. The permeable layer is at least partially in contact with the outside environment, and its tip extends outside the tank body to form a cathode terminal. This air cathode electrolyzer 42 generates sodium hypochlorite solution by electrolyzing a dilute brine solution and utilizing oxygen from the air. No hydrogen is generated during the electrolysis process, significantly improving operational safety and greatly reducing safety risks.

[0026] In one embodiment, such as Figures 1 to 3 As shown in the figure, the saturated brine preparation device includes a salt dissolving tank 1. The top of the salt dissolving tank 1 is provided with a water inlet and a salt inlet. The water inlet of the salt dissolving tank 1 is connected to a water replenishment device, which replenishes the soft water in the salt dissolving tank 1. The salt inlet of the salt dissolving tank 1 is connected to a salt feeding device, which adds salt to the salt dissolving tank 1.

[0027] In one embodiment, such as Figures 1 to 3 As shown, the bottom of the salt dissolving tank 1 is equipped with a salt dissolving water distribution pipe 2 and a salt dissolving filter 3. The salt dissolving water distribution pipe 2 is located above the salt dissolving filter 3 and is connected to the upper middle part of the salt dissolving tank 1 through a salt dissolving pipe 4. A salt dissolving pump 5 is installed on the salt dissolving pipe 4. The outlet of the salt dissolving filter 3 is connected to the pipeline mixer 7 through a saturated brine delivery pipe 6. A saturated brine metering pump 8, a first manual valve 9, and a saturated brine flow meter 10 are sequentially installed on the saturated brine delivery pipe 6 along the delivery direction of the saturated brine solution. When the salt dissolving pump 5 operates, it pumps the unsaturated brine in the salt dissolving tank 1 to the salt dissolving water distribution pipe 2. The salt dissolving water distribution pipe 2 uses the circulating brine solution to flush and stir the salt layer, accelerating the dissolution of the salt. The salt dissolving filter 3 filters the saturated brine solution, isolating the salt outside the salt dissolving filter 3. The saturated brine after passing through the salt dissolving filter 3 enters the saturated brine delivery pipe 6, and the saturated brine solution is pumped to the pipeline mixer 7 as needed by the saturated brine metering pump 8 and the saturated brine flow meter 10.

[0028] In one embodiment, such as Figures 1 to 3As shown, the water replenishment device includes a water softener 11. The inlet of the water softener 11 is connected to the tap water delivery pipe 12. The tap water delivery pipe 12 is provided with a second manual valve 13, a first Y-type filter 14 and a first pressure gauge 15 in sequence along the tap water delivery direction. The second manual valve 13 controls the opening and closing of the tap water delivery pipe 12. The first Y-type filter 14 filters the tap water. The first pressure gauge 15 monitors the water pressure in the tap water delivery pipe 12 in real time. The outlet of the water softener 11 is connected to the water inlet of the salt dissolving tank 1 through a water replenishment pipe 16. An ultrasonic level gauge 17 for level detection is installed on the top of the salt dissolving tank 1. After tap water is transported to the water softener 11 through the tap water delivery pipe 12, it is processed by the water softener 11 to produce softened water. When the ultrasonic level gauge 17 detects that the liquid level in the salt dissolving tank 1 is lower than the set low value, the softened water is transported to the salt dissolving tank 1 through the water replenishment pipe 16 to replenish the softened water. When the ultrasonic level gauge 17 detects that the liquid level in the salt dissolving tank 1 reaches the set high value, the replenishment of softened water to the salt dissolving tank 1 is stopped.

[0029] In this embodiment, the water supply pressure of the tap water delivery pipeline 12 is greater than 0.2 MPa to meet the water supply requirements of the system.

[0030] In one embodiment, such as Figure 1 and Figure 2 As shown, the salt feeding device includes a salt storage hopper 18, with a vacuum generator 19 located below it. The suction port of the vacuum generator 19 is connected to the discharge port of the salt storage hopper 18. The liquid inlet of the vacuum generator 19 is connected to the upper middle part of the salt dissolving tank 1 via a salt flushing pipe 20. The salt flushing pipe 20 is equipped with a salt feeding pump 21 and a third manual valve 22, which is located between the salt feeding pump 21 and the salt dissolving tank 1. The liquid outlet of the vacuum generator 19 is connected to the salt inlet of the salt dissolving tank 1 via a salt feeding pipe 23. When the salt in the salt dissolving tank 1 is insufficient, the salt feeding pump 21 operates, drawing unsaturated brine from the salt dissolving tank 1 to the vacuum generator 19. Under the negative pressure adsorption of the vacuum generator 19, the salt in the salt storage hopper 18 is drawn into the vacuum generator 19 from the suction port and transported to the salt dissolving tank 1 via the salt feeding pipe 23, thus realizing the automatic addition of salt to the salt dissolving tank 1.

[0031] In one embodiment, such as Figure 1 and Figure 2As shown, the salt storage hopper 18 has an inverted conical shell structure, and a flushing spray pipe 24 is provided inside the salt storage hopper 18. The flushing spray pipe 24 is an annular structure adapted to the contour of the inner wall of the salt storage hopper 18, and several spray holes are opened on the flushing spray pipe 24 facing the hopper wall of the salt storage hopper 18. The flushing spray pipe 24 is connected to the outlet of the salt pump 21 through a flushing branch pipe 25, and a flushing electric valve 26 is provided on the flushing branch pipe 25. When salt is added to the salt dissolving tank 1, the flushing electric valve 26 is opened, and the unsaturated brine solution is transported to the flushing spray pipe 24 through the flushing branch pipe 25. The flushing spray pipe 24 can flush the inner wall of the salt storage hopper 18, thereby preventing the raw salt from adhering to the inner wall of the salt storage hopper 18.

[0032] In one embodiment, such as Figure 5 As shown, several salt-dissolving water distribution pipes 2 are arranged side by side. These pipes are connected to the salt-dissolving pipeline 4 via a main water distribution pipe 27. Several water distribution holes 201 are opened on the side of each salt-dissolving water distribution pipe 2 facing the top of the salt-dissolving tank 1. These holes 201 are evenly arranged along the length of the pipe. During the online preparation of saturated brine, the salt-dissolving pump 5 operates, pumping the unsaturated brine from the salt-dissolving tank 1 to the main water distribution pipe 27, where it enters each salt-dissolving water distribution pipe 2. Finally, it is ejected from the water replenishment holes of each pipe, achieving the flushing and stirring of the salt layer, thus greatly accelerating the dissolution efficiency of the salt.

[0033] In one embodiment, such as Figure 5 As shown, the salt-dissolving water distribution pipe 2 is fixedly installed at the bottom of the salt-dissolving tank 1 using the support base 28. The main water distribution pipe 27 is located at the same end of several salt-dissolving water distribution pipes 2. One end of the salt-dissolving pipe 4 is connected to the middle and upper part of the salt-dissolving tank 1, and the other end of the salt-dissolving pipe 4 is connected to the inlet of the main water distribution pipe 27. The outlets of the main water distribution pipe 27 are respectively connected to one end of the salt-dissolving water distribution pipe 2. The end of the salt-dissolving water distribution pipe 2 away from the main water distribution pipe 27 is sealed and fixedly installed with a plug 29.

[0034] In one embodiment, such as Figures 6 to 12As shown, the salt-dissolving filter 3 includes an inner support tube 30 with several water passage holes 3001. A filter cotton layer 31 covering the water passage holes 3001 is provided outside the inner support tube 30. An outer permeable pipe 32 is fitted over the filter cotton layer 31. The inner diameter of the outer permeable pipe 32 is larger than the outer diameter of the filter cotton layer 31, and a filtration gap is formed between the inner wall of the outer permeable pipe 32 and the outer wall of the filter cotton layer 31. Several water passage holes are provided on the outer permeable pipe 32, and one end of the outer permeable pipe 32 is sealed. A port plug 33 is fixedly connected, and a port connector 34 is fixedly and sealed at the other end of the external water permeable pipe 32. The filter cotton layer 31 and the external water permeable pipe 32 are located between the port plug 33 and the port connector 34. The port connector 34 is provided with a clearance hole 3401 for the inner support pipe 30 to pass through at the end away from the port plug 33. The end of the inner support pipe 30 away from the port plug 33 passes through the clearance hole 3401 through the port connector 34 and is connected to the saturated brine conveying pipe 6. The external permeable pipe 32 performs primary filtration of the saturated brine solution, while the filter cotton layer 31 performs secondary filtration. After filtration, the saturated brine solution enters the inner support pipe 30 and is then output through the saturated brine delivery pipe 6. Furthermore, the filtration gap formed between the inner wall of the external permeable pipe 32 and the outer wall of the filter cotton layer 31 effectively prevents the permeable holes of the external permeable pipe 32 from becoming clogged, thus extending the service life of the salt filter 3. In addition, when backwashing the salt filter 3, the backwashing effect of the external permeable pipe 32 is improved, making the cleaning of the external permeable pipe 32 more thorough.

[0035] In one embodiment, such as Figures 6 to 9 As shown, the inner support pipe 30 includes a permeable section and a water conveying section. The permeable section is located between the port sealing member 33 and the port connector 34, and has several water passage holes 3001. The filter cotton layer 31 covers the permeable section, and the diameter of the clearance hole 3401 is adapted to the outer diameter of the inner support pipe 30. The water conveying section extends outward through the clearance hole 3401 through the port connector 34 and connects to the saturated brine conveying pipe 6. The saturated brine solution filtered by the filter cotton layer 31 enters the inner support pipe 30 through the water passage holes 3001 of the permeable section, and is then conveyed to the saturated brine conveying pipe 6 through the water conveying section.

[0036] In one embodiment, such as Figures 7 to 9 As shown, the water passage 3001 has an arc-shaped strip structure, and the water passage 3001 is inclinedly opened on the wall of the permeable section of the inner support pipe 30. At least one row of water passages 3001 is provided, and the water passages 3001 in each row are evenly arranged along the axial direction of the inner support pipe 30. This structure of the water passage 3001 not only ensures that the saturated brine solution can smoothly enter the inner support pipe 30, but also makes the overall structural strength of the inner support pipe 30 high.

[0037] In one embodiment, such asFigures 7 to 11 As shown, the filter cotton layer 31 is a PP cotton filter bag structure with one end closed and the other end having an insertion port. The inner diameter of the filter cotton layer 31 is adapted to the outer diameter of the inner support tube 30. The inner support tube 30 is fitted inside the filter cotton layer 31, and the end of the inner support tube 30 near the port sealing member 33 abuts against the closed end of the filter cotton layer 31. This filter cotton layer 31, made of PP cotton, is low in cost, has good filtration effect, and the filter bag structure is easy to fit onto the inner support tube 30, making assembly simple and convenient.

[0038] In one embodiment, such as Figures 6 to 8 , Figure 12 As shown, the external permeable pipe 32 has a curved mesh rigid pipe structure. The port sealing component 33 and the port connecting component 34 are respectively fitted onto both ends of the external permeable pipe 32, and both the port sealing component 33 and the port connecting component 34 are sealed and fixed to the external permeable pipe 32 using adhesive. The external permeable pipe 32 includes several inwardly protruding first curved ribs 3201 and several outwardly protruding second curved ribs 3202. The first curved ribs 3201 and the second curved ribs 3202 are integrally formed. The several first curved ribs 3201 and several second curved ribs 3202 are evenly arranged circumferentially, and the corresponding first curved ribs 3201 and second curved ribs 3202 are staggered to form permeable holes. Both the first curved rib 3201 and the second curved rib 3202 have a sinusoidal wave structure. Water-permeable holes are formed between the crests of the first curved rib 3201 and the troughs of the second curved rib 3202, as well as between the troughs of the first curved rib 3201 and the crests of the second curved rib 3202. Water collection troughs communicating with the water-permeable holes are formed between adjacent second curved ribs 3202. This external water-permeable pipe 32 not only provides good filtration of saturated salt water solutions but also has high structural strength, enabling it to protect the filter cotton layer 31 from compression.

[0039] In one embodiment, such as Figure 1 , Figure 3 and Figure 4 As shown, the saturated brine dilution device includes a dilution water tank 35. The inlet of the dilution water tank 35 is connected to the outlet of the water softener 11 via a soft water delivery pipe 36. The outlet of the dilution water tank 35 is connected to the pipeline mixer 7 via a dilution water delivery pipe 37. A dilution water pump 38, a fourth manual valve 39, and a dilution water flow meter 40 are sequentially installed on the dilution water delivery pipe 37 along the soft water delivery direction. The softened water obtained after treatment by the water softener 11 enters the salt dissolving tank 1 in one direction and is temporarily stored in the dilution water tank 35 in the other direction. When preparing sodium hypochlorite solution, the dilution water pump 38 operates, pumping the softened water in the dilution water tank 35 to the pipeline mixer 7 as needed. The softened water is fully mixed with the saturated brine solution in the pipeline mixer 7 according to the required flow ratio to obtain a dilute brine solution of the required concentration for electrolysis.

[0040] In one embodiment, such as Figure 1 and Figure 4 As shown, the inlet of the air cathode electrolyzer 42 is also connected to a drain pipe 44. A fifth manual valve 45 is installed on the drain pipe 44 to realize its opening and closing. Through the drain pipe 44 and the fifth manual valve 45, it is convenient to perform regular drainage and cleaning of the air cathode electrolyzer 42.

[0041] In one embodiment, such as Figure 13 , Figure 14 , Figures 16 to 21 As shown, an air cathode electrolytic cell 42 is provided. The cell body includes a connecting body 48. An anode holding plate 49 is sealed and fixedly connected to one side of the connecting body 48. A cathode 52 is fixedly installed on the other side of the connecting body 48 through a cathode holding frame 51 and is sealed to the connecting body 48. The catalyst layer of the cathode 52 is disposed close to the connecting body 48, and the air permeable layer of the cathode 52 is close to the cathode holding frame 51. The cathode holding frame 51 has a vent window for contacting the cathode 52 with the outside air. A receiving cavity is formed between the connecting body 48, the anode holding plate 49, and the cathode 52. A liquid inlet communicating with the receiving cavity is opened at the bottom of the connecting body 48, and the liquid inlet of the connecting body 48 is connected to the electrolyte conveying pipe 41. A liquid outlet communicating with the receiving cavity is opened at the top of the connecting body 48, and the liquid outlet of the connecting body 48 is connected to the sodium hypochlorite conveying pipe 46. The anode 50 is located between the anode holding plate 49 and the connecting body 48, and the anode 50 is located inside the receiving cavity. The tank structure is simple and strong. At the anode 50, a chlorine evolution reaction occurs, oxidizing chloride ions to generate chlorine gas. At the cathode 52, an oxygen reduction reaction occurs, generating hydroxide ions (OH-). - The process generates sodium hydroxide, replacing the traditional hydrogen evolution reaction. In the containment chamber of the air cathode electrolytic cell 42, chlorine gas rapidly dissolves and reacts with sodium hydroxide to generate sodium hypochlorite.

[0042] Cathode: O2 + 2H2O + 4e - →4OH - ； Anode: 2Cl - 2e - →Cl 2； Solution reaction: 2NaOH + Cl₂ = NaCl + NaClO + H₂O ； In one embodiment, such as Figures 13 to 20As shown, an anode clearance groove 4801 adapted to the anode 50 is provided on one side of the connecting body 48. The anode 50 is installed on one side of the connecting body 48 through the anode clearance groove 4801 and is sealed to the connecting body 48 by the anode sealing strip 53. There is a communication gap 54 between the two sides of the connecting anode and the connecting body 48 for the electrolyte to pass through. The anode holding plate 49 is sealed to the connecting body 48 and the anode 50 by the anode sealing ring 55. The side of the anode holding plate 49 near the anode 50 has a liquid storage tank 4901. The anode 50 divides the receiving cavity into a first chamber and a second chamber. The anode holding plate 49 forms the first chamber by its liquid storage tank 4901 and the anode 50. The second chamber is formed by the anode 50, the connecting body 48 and the cathode 52. The first chamber and the second chamber are connected by the communication gap 54. Thus, while increasing the receiving cavity space, both sides of the anode 50 are in contact with the electrolyte, which greatly improves the electrolysis efficiency.

[0043] In one embodiment, such as Figures 16 to 20 As shown, a sealing strip mounting groove 4802 is provided on the top and bottom of one side of the connecting body 48. The anode sealing strip 53 is installed in the sealing strip mounting groove 4802. A first sealing ring mounting groove 4902 is provided on the side of the anode holding plate 49 near the anode 50. The anode sealing ring 55 is installed in the first sealing ring mounting groove 4902.

[0044] In one embodiment, such as Figures 13 to 19 , Figure 21 As shown, a cathode clearance groove 4803 adapted to the cathode 52 is provided on the other side of the connecting body 48. The cathode 52 is installed on the other side of the connecting body 48 through the cathode clearance groove 4803 and is sealed to the connecting body 48 by the first cathode sealing ring 56. The cathode holding frame 51 is sealed to the cathode 52 by the second cathode sealing ring 57. The cathode holding frame 51 has an integrally formed cathode holding strip 5101. The cathode holding strip 5101 divides the vent window into several venting areas. The cathode 52 is exposed to the air through the venting areas. The cathode holding strip 5101 greatly improves the installation strength of the cathode 52.

[0045] In one embodiment, such as Figures 16 to 19 , Figure 21 As shown, a second sealing ring mounting groove 4804 is provided on the other side of the connecting body 48, and the first cathode sealing ring 56 is installed in the second sealing ring mounting groove 4804. A third sealing ring mounting groove 5102 is provided on the side of the cathode holding frame 51 near the cathode 52, and the second cathode sealing ring 57 is installed in the third sealing ring mounting groove 5102.

[0046] In one embodiment, both the anode holding plate 49 and the cathode holding frame 51 are fixedly connected to the connecting body 48 using connecting screws and nuts, making assembly simple and convenient, and providing high structural strength.

[0047] In some embodiments, the cathode is a layered structure formed by pressing together a catalyst layer, a current collector layer, and a permeable layer; wherein, the catalyst layer comprises oxygen reduction electrocatalyst powder, conductive carbon black, and a hydrophobic material, and the catalyst layer is a film-like structure formed by pressing a mixture of oxygen reduction electrocatalyst powder, conductive carbon black, and a hydrophobic material, or, the catalyst layer is a thin layered structure formed by spraying a mixture of oxygen reduction electrocatalyst powder, conductive carbon black, and a hydrophobic material and then hot-pressing it; the permeable layer comprises conductive carbon black, a binder, and a hydrophobic material, and the permeable layer is a film-like structure formed by pressing a mixture of conductive carbon black, a binder, a hydrophobic material, and a pore-forming agent into a film and then decomposing and removing the pore-forming agent; the current collector layer is a titanium mesh structure.

[0048] In one embodiment, the catalyst layer is a membrane structure obtained by pressing a mixture of silver, platinum, conductive carbon black and PTFE powder, and the thickness of the catalyst layer is 0.2-1 mm; the current collector layer is a titanium mesh structure; the air permeable layer is a membrane structure obtained by pressing a mixture of conductive carbon black and PTFE slurry, and the thickness of the air permeable layer is 0.8-1 mm.

[0049] Specifically, elemental silver powder, platinum powder, conductive carbon black, and PTFE powder with a purity greater than 99.95% are weighed out according to a mass ratio of 1:1:2:1.5. These powders are then fed into a grinding machine and thoroughly ground to obtain a mixed powder. The mixed powder is then poured into a mold, heated, and pressed to form the catalytic layer. Elemental conductive carbon black and PTFE powder with a purity greater than 99.95% are weighed out according to a mass ratio of 1:1.2:0.5. The catalyst layer, current collector layer, and permeable layer are combined with ammonium carbonate powder, and then conductive carbon black, PTFE powder, and ammonium carbonate powder are put into a grinding equipment and ground thoroughly to obtain a mixed powder. Then, the mixed powder is compounded into a slurry by hydrothermal method, and the slurry is poured into a mold. The mold is heated and pressed into a film. Then, the ammonium carbonate is decomposed and released by baking, leaving air channels to obtain a permeable layer. Finally, the catalyst layer, current collector layer and permeable layer are pressed into a whole cathode 52. Thus, the permeability and electrolysis efficiency of the prepared cathode 52 are greatly improved.

[0050] In another embodiment, the current collector layer is a titanium mesh structure; the permeable layer is a membrane structure formed by pressing a mixed slurry of conductive carbon black and PTFE, and the thickness of the permeable layer is 0.8-1 mm; the catalyst layer is a thin-layer structure formed by spraying a mixed slurry of 40% platinum-carbon catalyst, conductive carbon black, and PTFE onto the current collector layer and then hot-pressing it, and the Pt loading density of the catalyst layer reaches 0.2 mg / cm³. 2 .

[0051] Specifically, first, elemental conductive carbon black with a purity greater than 99.95%, PTFE powder, and ammonium carbonate powder are weighed out according to a mass ratio of 1:1.2:0.5. Then, the conductive carbon black, PTFE powder, and ammonium carbonate powder are added to a grinding device and thoroughly ground to obtain a mixed powder. Next, the mixed powder is compounded into a slurry using a hydrothermal method. The slurry is then poured into a mold, and the mold is heated to press it into a film. Afterward, baking causes the ammonium carbonate to decompose and escape, leaving air channels to obtain a permeable layer. Then, the obtained permeable layer and a titanium mesh current collector layer are first pressed together to form a tight structure, with the permeable layer located on one side of the current collector layer. Then, 40% platinum-carbon catalyst, PTFE powder, and conductive carbon black are dispersed in an isopropanol solution in a ratio of 1:0.2:1 and ultrasonically dispersed into a uniform slurry. This slurry is then ultrasonically sprayed onto the other side of the current collector layer to achieve a Pt loading density of 0.2 mg / cm³. 2 Finally, the cathode is formed by hot pressing to create a dense layered structure.

[0052] In another embodiment, such as Figure 15 As shown, there are two air cathode electrolytic cells 42. The anode 50 of the first air cathode electrolytic cell 42 is electrically connected to the positive terminal of the rectifier power supply 43. The cathode 52 of the first air cathode electrolytic cell 42 is electrically connected to the anode 50 of the second air cathode electrolytic cell 42, and the cathode 52 of the second air cathode electrolytic cell 42 is electrically connected to the negative terminal of the rectifier power supply 43. The inlet of the first air cathode electrolytic cell 42 is connected to the electrolyte delivery pipe 41, and the outlet of the first air cathode electrolytic cell 42 is connected to the inlet of the second air cathode electrolytic cell 42 via the inter-cell delivery pipe 58. The outlet of the second air cathode electrolytic cell 42 is connected to the sodium hypochlorite delivery pipe 46. Of course, depending on the specifications of the air cathode electrolytic cell 42 and the actual electrolysis rate requirements, the number of air cathode electrolytic cells 42 can also be set to three, four, five, etc.

[0053] In one embodiment, such as Figure 1 and Figure 4As shown, the metering and dosing device includes a sodium hypochlorite pumping pipe 59 and a sodium hypochlorite return pipe 60. The sodium hypochlorite pumping pipe 59 is connected to the outlet of the sodium hypochlorite storage tank 47. Along the pumping direction of the sodium hypochlorite solution, the sodium hypochlorite pumping pipe 59 is sequentially equipped with a sixth manual valve 61, a second Y-type filter 62, a dosing metering pump 63, a second pressure gauge 64, and a back pressure valve 65. One end of the sodium hypochlorite return pipe 60 is connected to the outlet of the dosing metering pump 63, and the other end of the sodium hypochlorite return pipe 60 is connected to the inlet of the dosing metering pump 63. The sodium hypochlorite return pipe 60 is equipped with a pressure relief valve 66. The outlet of the dosing metering pump 63 is also connected to a pulse damper 68 through a seventh manual valve 67. In use, the metering and dosing device can meter and pump the sodium hypochlorite solution in the sodium hypochlorite storage tank 47 as needed for dosing. A second Y-type filter 62 installed on the sodium hypochlorite pumping pipeline 59 can effectively filter the sodium hypochlorite solution. The dosing metering pump 63 pumps the sodium hypochlorite solution, and a second pressure gauge 64 detects the pressure in the sodium hypochlorite pumping pipeline 59. A pulse damper 68 is connected to the outlet of the dosing metering pump 63, which absorbs and buffers pressure pulses and flow fluctuations generated during the sodium hypochlorite solution transportation process, reducing the vibration amplitude of the sodium hypochlorite pumping pipeline 59 and improving the transportation stability of the sodium hypochlorite solution. A back pressure valve 65 is installed on the sodium hypochlorite pumping pipeline 59. In conjunction with the pulse damper 68, it can reduce the peak value of flow velocity fluctuations and ensure the stability of the flow rate of sodium hypochlorite solution delivered by the metering pump 63. When the pressure in the sodium hypochlorite pumping pipeline 59 or the metering pump 63 is unstable, it can maintain the required pressure in the pipeline, enabling the metering pump 63 to output the normal flow rate. The outlet of the metering pump 63 is connected to the sodium hypochlorite return pipeline 60 and the pressure relief valve 66 installed on the sodium hypochlorite return pipeline 60. When the pressure in the sodium hypochlorite pumping pipeline 59 is too high, the sodium hypochlorite solution flows back to the inlet of the metering pump 63 through the sodium hypochlorite return pipeline 60, thereby ensuring that the delivery pressure in the sodium hypochlorite pumping pipeline 59 is stable and realizing the pumping and use of sodium hypochlorite solution according to the required flow rate.

[0054] This invention also provides a process for preparing sodium hypochlorite using the aforementioned hydrogen-free sodium hypochlorite preparation system, comprising the following steps: S1. Tap water is delivered to water softener 11. After being processed by water softener 11, the softened water is delivered to salt dissolving tank 1 and dilution water tank 35 in two separate streams.

[0055] In this step, the water supply pressure of the tap water is greater than 0.2 MPa, and the hardness of the softened water after being treated by the water softener 11 is reduced to below 10 ppm. The hardness of the softened water is calculated based on CaCO3 in the softened water. S2. The salt pump 21 operates, adding the salt in the salt storage hopper 18 into the salt dissolving tank 1.

[0056] S3. The salt dissolving pump 5 operates, dissolving the salt in the salt dissolving tank 1 through the salt dissolving water distribution pipe 2, and simultaneously filtering the salt through the salt dissolving filter 3 to obtain a saturated salt solution. When the salt in the salt dissolving tank 1 is insufficient, step S2 is repeated.

[0057] In steps S2 and S3, the amount of salt added to the salt dissolving tank 1 is based on the height of the salt body at least covering the salt dissolving water distribution pipe 2.

[0058] S4. The saturated brine solution obtained after filtration through the salt dissolving filter 3 is transported to the pipeline mixer 7. At the same time, the softened water in the dilution water tank 35 is transported to the pipeline mixer 7. The pipeline mixer 7 is used to mix the saturated brine solution and the softened water to obtain a dilute brine solution.

[0059] In this step, the concentration of the dilute salt solution is 3%.

[0060] S5. The dilute salt solution is transported to the air cathode electrolytic cell 42, and the dilute salt solution is electrolyzed by the air cathode electrolytic cell 42 to obtain sodium hypochlorite solution.

[0061] In this step, the effective chlorine concentration of the sodium hypochlorite solution ranges from 8000 to 10000 ppm.

[0062] S6. Transfer the sodium hypochlorite solution to sodium hypochlorite storage tank 47 for temporary storage.

[0063] S7. The sodium hypochlorite solution in the sodium hypochlorite storage tank 47 is metered and pumped as needed for use.

[0064] Based on the above structure, the hypochlorous acid preparation system for the electrolytic acid electrolyte, during operation, softened water is prepared through a water softener 11. The softened water is transported in two ways: one to a salt dissolving tank 1 for dissolving salt, and the other to a dilution water tank 35 for temporary storage. An automatic salt addition device is used to add salt to the salt dissolving tank 1. Rapid dissolution of salt in the salt dissolving tank 1 and online preparation of saturated brine solution are achieved through a salt dissolving water distribution pipe 2 and a salt dissolving filter 3. Then, a saturated brine metering pump 8 transports the saturated brine solution obtained after filtration by the salt dissolving filter 3 to a pipeline mixer 7. Simultaneously, a dilution water pump 38 transports the softened water from the dilution water tank 35 to the pipeline mixer 7. The system then operates within the pipeline mixer 7. In this process, saturated brine solution and softened water are thoroughly mixed to prepare a dilute brine solution. This solution is then introduced into an air cathode electrolytic cell 42. The anode 50 is a coated titanium anode, where a chlorine evolution reaction occurs, producing chlorine gas. The cathode 52 is a gas diffusion electrode with a three-phase interface, where an oxygen reduction reaction occurs, producing sodium hydroxide. The anode and cathode products mix within the containment chamber of the air cathode electrolytic cell 42 to generate sodium hypochlorite. Finally, the sodium hypochlorite solution is temporarily stored in a sodium hypochlorite storage tank 47. This process enables the online preparation of sodium hypochlorite solution. When needed, the sodium hypochlorite solution in the storage tank 47 is metered and pumped using a metering and dosing device for addition and use.

[0065] This sodium hypochlorite preparation system and process, which eliminates hydrogen generation, enables online preparation of the electrolyte and sodium hypochlorite solution via electrolysis. The system and process are simple and convenient, resulting in efficient and safe sodium hypochlorite solution preparation. The included air cathode electrolyzer 42 optimizes the electrolysis process. Compared to traditional methods that use a sodium hypochlorite generator to electrolyze brine, this air cathode electrolyzer 42 generates sodium hypochlorite solution by electrolyzing a dilute salt solution and utilizing oxygen from the air. No hydrogen is generated during electrolysis, avoiding the risk of explosion and significantly improving operational safety. It is also safer and more environmentally friendly. Furthermore, the entire preparation process requires only simple raw materials such as electricity, water, and salt. On-site online preparation reduces transportation and storage costs, making it more economical for long-term use. It is applicable to various scenarios, such as drinking water disinfection and wastewater treatment, and its output can be adjusted according to demand to suit different scales of application.

[0066] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the invention. Furthermore, it should be understood that after reading the technical description of this invention, those skilled in the art can make various alterations, modifications, and / or variations to the invention, and all such equivalent forms also fall within the scope of protection defined by the appended claims.

Claims

1. A sodium hypochlorite production system without hydrogen gas generation, characterized by, The application relates to a salt water electrolysis device, which comprises a pipeline mixer connected with a liquid inlet of the salt water electrolysis device through an electrolyte conveying pipeline, a saturated salt water preparation device and a saturated salt water dilution device connected with liquid inlets of the pipeline mixer respectively, a sodium hypochlorite storage tank connected with a liquid outlet of the salt water electrolysis device through a sodium hypochlorite conveying pipeline, and a metering and adding device connected with a liquid outlet of the sodium hypochlorite storage tank. The salt water electrolysis device comprises an air cathode electrolytic cell and a rectifier power supply, the air cathode electrolytic cell is provided with at least one, the air cathode electrolytic cell comprises a cell body, the cell body has a containing cavity for containing electrolyte, and an anode and a cathode electrically connected with the rectifier power supply are fixedly installed on the cell body. The anode comprises a titanium base plate, a ruthenium iridium noble metal oxide coating is arranged outside the titanium base plate, the anode is located in the containing cavity, and a top end of the anode extends out of the cell body to form an anode wiring end. The cathode comprises a catalytic layer, a current collector layer and a gas permeable layer, the current collector layer is located between the catalytic layer and the gas permeable layer, the catalytic layer is close to the anode and is in contact with the containing cavity, the gas permeable layer is at least partially in contact with the outside, and a top end of the cathode extends out of the cell body to form a cathode wiring end.

2. The sodium hypochlorite generation system without hydrogen gas production according to claim 1, characterized by, The saturated salt water preparation device comprises a salt dissolving tank, a water inlet and a salt feeding port are arranged on the top of the salt dissolving tank, a water supplementing device is connected with the water inlet of the salt dissolving tank, and a salt feeding device is connected with the salt feeding port of the salt dissolving tank. A salt dissolving and water distributing pipeline and a salt dissolving filter are arranged on the bottom of the salt dissolving tank, the salt dissolving and water distributing pipeline is located above the salt dissolving filter, the salt dissolving and water distributing pipeline is connected with the middle and upper part of the salt dissolving tank through a salt dissolving pipeline, a salt dissolving pump is arranged on the salt dissolving pipeline, a saturated salt water conveying pipeline is connected with the liquid outlet of the salt dissolving filter and the pipeline mixer, a saturated salt water metering pump, a first hand valve and a saturated salt water flowmeter are sequentially arranged on the saturated salt water conveying pipeline along the conveying direction of the saturated salt water solution.

3. The sodium hypochlorite generation system without hydrogen gas production according to claim 2, characterized by, The water supplementing device comprises a water softener, a tap water conveying pipeline is connected with the liquid inlet of the water softener, a second hand valve, a first Y-shaped filter and a first pressure gauge are sequentially arranged on the tap water conveying pipeline along the conveying direction of the tap water, the liquid outlet of the water softener is connected with the water inlet of the salt dissolving tank through a water supplementing pipeline, and an ultrasonic liquid level meter for realizing liquid level detection is arranged on the top of the salt dissolving tank. The salt feeding device comprises a salt storage hopper, a vacuum generator is arranged below the salt storage hopper, a material suction port of the vacuum generator is connected with a material outlet of the salt storage hopper, a salt flushing pipeline is connected with the middle and upper part of the salt dissolving tank through the liquid inlet of the vacuum generator, a salt feeding pump and a third hand valve are arranged on the salt flushing pipeline, the third hand valve is located between the salt feeding pump and the salt dissolving tank, and a salt feeding pipeline is connected with the salt feeding port of the salt dissolving tank through the liquid outlet of the vacuum generator. The salt storage hopper is a reverse conical shell structure, and a flushing spray pipe is arranged in the salt storage hopper.

4. The sodium hypochlorite generation system without hydrogen gas production according to claim 3, characterized by, The salt dissolving and water distributing pipes are communicated with the salt dissolving pipe through a water distribution main pipe, and the salt dissolving and water distributing pipes are provided with a plurality of water distribution holes on one side of the top of the salt dissolving tank. The salt dissolving filter comprises an inner support pipe, a plurality of water passing holes are formed in the inner support pipe, a filter cotton layer covering the water passing holes is arranged outside the inner support pipe, an outer water permeable pipe is sleeved outside the filter cotton layer, the inner diameter of the outer water permeable pipe is larger than the outer diameter of the filter cotton layer, a filter gap is formed between the inner wall of the outer water permeable pipe and the outer wall of the filter cotton layer, a plurality of water permeable holes are formed in the outer water permeable pipe, one end of the outer water permeable pipe is sealingly and fixedly connected with a port blocking piece, the other end of the outer water permeable pipe is sealingly and fixedly connected with a port connecting piece, the filter cotton layer and the outer water permeable pipe are located between the port blocking piece and the port connecting piece, and the end of the port connecting piece away from the port blocking piece is provided with a avoiding hole for the inner support pipe to pass through, and one end of the inner support pipe away from the port blocking piece penetrates through the port connecting piece through the avoiding hole and is communicated with the saturated brine conveying pipe.

5. The sodium hypochlorite generation system without hydrogen gas production according to claim 4, characterized by, The saturated brine diluting device comprises a diluting water tank, the water inlet of the diluting water tank is communicated with the liquid outlet of the water softener through a soft water conveying pipe, the water outlet of the diluting water tank is communicated with the pipe mixer through a diluting water conveying pipe, and the diluting water conveying pipe is sequentially provided with a diluting water pump, a fourth manual valve and a diluting water flow meter along the soft water conveying direction.

6. The sodium hypochlorite generation system without hydrogen gas production according to any one of claims 1 to 5, characterized in that, The tank body comprises a connecting main body, one side of the connecting main body is sealingly and fixedly connected with an anode pressing plate, a cathode is fixedly installed on the other side of the connecting main body through a cathode pressing frame and is sealingly connected with the connecting main body, the catalytic layer of the cathode is arranged close to the connecting main body, the air permeable layer of the cathode is arranged close to the cathode pressing frame, and the cathode pressing frame has an air permeable window for realizing the contact between the cathode and the external air. The connecting main body, the anode pressing plate and the cathode form the containing cavity therebetween, the bottom of the connecting main body is provided with a liquid inlet communicated with the containing cavity, the liquid inlet of the connecting main body is communicated with the electrolyte conveying pipe, the top of the connecting main body is provided with a liquid outlet communicated with the containing cavity, and the liquid outlet of the connecting main body is communicated with the sodium hypochlorite conveying pipe. The anode is located between the anode pressing plate and the connecting main body and in the containing cavity.

7. The sodium hypochlorite generation system without hydrogen gas production according to claim 6, characterized by, The connecting body is provided with an anode avoiding groove on one side, the anode is installed on one side of the connecting body through the anode avoiding groove and is sealed and connected with the connecting body by an anode sealing strip, and the two side edges of the connecting anode have a communication gap with the connecting body for electrolyte to pass through, the anode pressing plate is sealed and connected with the connecting body and the anode by an anode sealing ring, and the side of the anode pressing plate close to the anode has a liquid storage groove, the anode divides the containing cavity into a first chamber and a second chamber, the anode pressing plate and the anode surrounding the liquid storage groove form the first chamber, the anode, the connecting body and the cathode surrounding the liquid storage groove form the second chamber, and the first chamber and the second chamber are communicated through the communication gap; The other side of the connecting body is provided with a cathode avoiding groove matched with the cathode, the cathode is installed on the other side of the connecting body through the cathode avoiding groove and is sealed and connected with the connecting body by a first cathode sealing ring, the cathode pressing frame is sealed and connected with the cathode by a second cathode sealing ring, and the cathode pressing frame has an integrally formed cathode pressing strip, and the cathode pressing strip divides the air permeable window into a plurality of air permeable areas.

8. The sodium hypochlorite generation system without hydrogen gas production according to claim 7, characterized by, The cathode is a layered structure obtained by pressing the catalytic layer, the current collector layer and the air permeable layer together; The catalytic layer comprises oxygen reduction electrocatalyst powder, conductive carbon black and hydrophobic material, and the catalytic layer is a membrane structure obtained by pressing mixed powder of the oxygen reduction electrocatalyst powder, the conductive carbon black and the hydrophobic material, or the catalytic layer is a thin layered structure obtained by spraying mixed slurry of the oxygen reduction electrocatalyst powder, the conductive carbon black and the hydrophobic material and then hot pressing; The air permeable layer comprises conductive carbon black, a binder and a hydrophobic material, and the air permeable layer is a membrane structure obtained by pressing mixed slurry of the conductive carbon black, the binder, the hydrophobic material and a pore former and then removing the pore former; The current collector layer is a titanium mesh structure.

9. The sodium hypochlorite generation system without hydrogen gas production according to claim 8, characterized by, The metering device comprises a sodium hypochlorite pumping pipeline and a sodium hypochlorite return pipeline, the sodium hypochlorite pumping pipeline is communicated with a liquid outlet of the sodium hypochlorite storage tank, and a sixth manual valve, a second Y-shaped filter, a metering pump, a second pressure gauge and a back pressure valve are sequentially arranged on the sodium hypochlorite pumping pipeline along the pumping direction of the sodium hypochlorite solution, one end of the sodium hypochlorite return pipeline is communicated with a liquid outlet of the metering pump, the other end of the sodium hypochlorite return pipeline is communicated with a liquid inlet of the metering pump, and a pressure relief valve is arranged on the sodium hypochlorite return pipeline, and the liquid outlet of the metering pump is further communicated with a pulse damper through a seventh manual valve.

10. A process for the production of sodium hypochlorite using the sodium hypochlorite production system without hydrogen gas production according to any one of claims 1 to 9, characterized in that, The method comprises the following steps: S1, tap water is transported to a water softener, and after treatment by the water softener, softened water is transported to a salt dissolving tank and a dilution water tank in two ways; S2, the upper salt pump works to add the salt in the salt storage hopper to the salt dissolving tank; S3, the salt dissolving pump works, the salt in the salt dissolving tank is dissolved through the salt dissolving water pipe, and the salt is filtered by using the salt dissolving filter, a saturated brine solution is prepared, and when the salt in the salt dissolving tank is insufficient, the step S2 is repeated; S4, the saturated brine solution prepared after being filtered by the salt dissolving filter is transported to the pipeline mixer, at the same time, the softened water in the dilution water tank is transported to the pipeline mixer, the saturated brine solution and the softened water are mixed by using the pipeline mixer, and a dilute brine solution is prepared; S5, the dilute brine solution is transported to the air cathode electrolytic cell, and the dilute brine solution is electrolyzed by using the air cathode electrolytic cell, and a sodium hypochlorite solution is prepared; S6, the sodium hypochlorite solution is transported to the sodium hypochlorite storage tank for temporary storage; S7, according to the requirement, the sodium hypochlorite solution in the sodium hypochlorite storage tank is metered and pumped for use.

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